The present invention generally relates to apparatus and methods for identification and verification. More particularly, the present invention relates to apparatus and methods for detecting an element or compound intrinsically presentxe2x80x94or extrinsically addedxe2x80x94in an article or product by using X-ray fluorescence to identify and verify that article or product. Even more particularly, the present invention relates to secure documents and methods and apparatus for making the same.
There has been significant interest in apparatus and methods for identifying and verifying various articles or products such as explosives, ammunition, paint, petroleum products, and documents. Known methods used to identify and verify generally involve adding and detecting materials like code-bearing microparticles, bulk chemical substances, and radioactive substances. Other methods used for identifying and verifying articles include those described in U.S. Pat. Nos. 6,030,657, 6,024,200, 6,007,744, 6,005,915, 5,849,590, 5,760,394, 5,677,187, 5,474,937, 5,301,044, 5,208,630, 5,057,268, 4,862,143, 4,390,452, 4,363,965, and 4,045,676, as well as European Patent Application Nos. 0911626 and 0911627, the disclosures of which are incorporated herein by reference.
It is also known to apply materials to articles in order to track, for example, point of origin, authenticity, and their distribution. In one method, inks which are transparent in visible light are sometimes applied to materials and the presence (or absence) of the ink is revealed by ultraviolet or infrared fluorescence. Other methods include implanting microscopic additives that can be detected optically. However, detecting these materials is primarily based on optical or photometric measurements.
Unfortunately, many of the apparatus and methods for identifying and verifying articles using such materials (called taggants) are unsatisfactory for several reasons. First, they are often difficult and time-consuming. In many instances, a sample of the article must be sent to an off-site laboratory for analysis. In other instances, the apparatus are often expensive, large, and difficult to operate. In yet other instances, the taggant used is radioactive, causing serious health concerns.
The known apparatus and methods for identification and verification are also unsatisfactory because they require a xe2x80x9cline-of-sightxe2x80x9d analysis method. This line of sight requirement entails that the apparatus must be able to xe2x80x9cseexe2x80x9d the taggant in order to detect it. This can be detracting when it would be desirable to detect the taggant without having to see the taggant, e.g., such as when the taggant is located in the middle of large package with packaging and labels xe2x80x9ccoveringxe2x80x9d the taggant.
The present invention provides an apparatus and method in which one or more taggants that are intrinsically locatedxe2x80x94or extrinsically placedxe2x80x94in an article or product are detected by x-ray fluorescence analysis to identify or verify the article or its point of manufacture. The taggant is manufactured as part of the article or the taggant is placed into a coating, packaging, label, or otherwise embedded within the article for the purpose of later verifying the presence or absence of these elements by x-ray fluorescence to determine the unique elemental composition of the taggant within these articles.
By using x-ray fluorescence analysis, the apparatus and methods of the present invention are simple and easy to use, as well as provide detection by a non line-of-sight method to establish the origin of materials, point of manufacture, authenticity, verification, or product security. The present invention is extremely advantageous because it is difficult to replicate, simulate, alter, transpose, or tamper with. Further, it can be easily recognized by a user in either overt or covert form, easily verified by a manufacturer or issuer, and easily applied to various forms of media in the articles.